asymptotically exact and nonlocal third order nonlinear evolution equations are derivedfor two counterpropagating surface capillary gravity wave packets in deep water in thepresence of wind flowing over water.from these evolution equations stability analysis ismade for a uniform standing surface capillary gravity wave trains for longitudinal perturbation. instability condition is obtained and g...

iran is situated in one of the world's seismic regions and the possibility of destructive earthquakes in most regions of the country has given great significance to recognition of iranian seismic nature from a seismic and seismotectonic standpoint. study of the crust and upper mantle velocity structure in the iranian plateau provides better understanding of its evolution and tectonic histo...

The local resonances of a free isotropic elastic plate are investigated using laser ultrasonic techniques. Experimental results are interpreted in terms of zero group velocity Lamb modes and edge mode. At a distance from the edge larger than the plate thickness a sharp resonance is observed at the frequency where the group velocity of the first symmetrical Lamb mode vanishes. Close to the edge ...

This paper presents a systematic and general method for Lamb wave-based crack size quantification using finite element simulations and Bayesian updating. The method consists of construction of a baseline quantification model using finite element simulation data and Bayesian updating with limited Lamb wave data from target structure. The baseline model correlates two proposed damage sensitive fe...

The paper is devoted to theoretical and experimental investigations of Lamb wave excitation and propagation in multilayered carbon fiber-reinforced plastic plates with obstacles. The theoretical modeling is performed in the context of general linear elasticity for three-dimensional laminate anisotropic media. It is based on the integral and asymptotic representations in terms of Green’s matrix ...

We introduce a high-order discontinuous Galerkin (dG) scheme for the numerical solution of three-dimensional (3D) wave propagation problems in coupled elastic-acoustic media. A velocity-strain formulation is used, which allows for the solution of the acoustic and elastic wave equations within the same unified framework. Careful attention is directed at the derivation of a numerical flux that pr...

Asymptotically exact and nonlocal fourth order nonlinear evolution equations are derived for two coupled fourth order nonlinear evolution equations have been derived in deep water for two capillary-gravity wave packets propagating in the same direction in the presence of wind flowing over water.We have used a general method, based on Zakharov integral equation.On the basis of these evolution eq...

Experimental Study of Fine Frequency Selection Techniques for Piezoelectric Aluminum Nitride Lamb Wave Resonators by Ting-Ta Yen Master of Science, Plan II in Electrical Engineering and Computer Sciences University of California, Berkeley Professor Albert P. Pisano, Chair Strong demand for high-Q resonators and filters in mobile wireless communication systems has initiated various research on r...

A time–frequency analysis-based signal processing study for detecting active corrosion in aluminum plate-like structure utilizing the broadband piezoelectric wafer active sensors is presented in this article. Tests were conducted on an aluminum plate with a network of sensors installed on one side of the plate for Lamb wave generation and reception. The corrosion was emulated as material loss o...

Cost-effective and reliable damage detection is critical for the utilization of composite materials. This paper presents part of an experimental and analytical survey of candidate methods for in-situ damage detection of composite materials. Results are presented for the optimization of Lamb wave techniques applied to quasi-isotropic graphite/epoxy specimens containing representative damage mode...